ayuh,.... Ya haven't even bought it yet....
Just buy newer insteada thinkin' repower/ refitting an old hull....
The only way to do these kinda up-grades is to buy a donor boat for it's driveline, 'n junk it...
Buyin' newer now, is about 10 times cheaper than buyin' junk, 'n refitting it....
Swappin' a motor is reasonably involved,.. 'n expensive....
Up-gradin' the transom 'n drive is guttin' the hull to it's bowls, 'n replacin' everything....